Thumbnail generating feature may prevent media files copying/deleting on MTP device?

I have a New HTC One(M7), which is a Android 4.4.3 smart phone. I've installed the latest HTC Sync Manager so I can connect the phone with a USB cable to my PC(Win 8.1).

When I try to copy media files from PC to M7, or delete a media file from it, the process hangs. Then I noticed that there is a LAV splitter icon appeared in the notification area. So I uninstalled K-lite Codec Pack 10.8.0, and the problem is gone. My guess is that File Explorer tried to generate thumbnail of the file, but in MTP mode, only one file can be accessed at a time. So it failed and caused File Explorer to hang.

I have another PC with Windows Server 2012 R2(the core is the same with win 8.1) and KCP 10.8.0 installed, and I can copy/delete media files without problem, so I'm not sure if it is a bug. I reported here for your reference.

It strange that LAV Splitter got used, since the codec pack uses Icaros for thumbnailing, and that does not use any DirectShow filters at all. What kind of file extension(s) trigger the problem? Perhaps it got used because a file is being converted?

You could try installing the codec pack without the Icaros PropertyHandler shell extension. That may lock files for a short duration. The Icaros ThumbnailProvider should normally not interfere with any Explorer copy/move operations. You could disable that as well if disabling the PropertyHandler is not enough.

KCP does not contain Icaros, nor does it extend thumbnailing functionality beyond what Windows supports natively afaik.

I DID see the dialog about converting the file when copying, but I chose to copy as-is.

I'll try your method when I have time. Thanks for your help.

Let me know the results.